Optical Light Curve of the Type I[CLC]a[/CLC] Supernova 1998[CLC]bu[/CLC] in M96 and the Supernova Calibration of the Hubble Constant

We present the UBV ( RI ) KC light curves of the Type Ia supernova SN 1998bu, which appeared in the nearby galaxy M96 (NGC 3368). M96 is a spiral galaxy in the Leo I group that has a Cepheid-based distance. Our photometry allows us to calculate the absolute magnitude and reddening of this supernova. These data, when combined with measurements of the four other well-observed supernovae with Cepheid-based distances, allow us to calculate the Hubble constant with respect to the Hubble flow defined by the distant Calán/Tololo Type Ia sample. We find a Hubble constant of 63.9 ± 2.2(internal) ± 3.5(external) km s -1 Mpc -1 , consistent with most previous estimates based on Type Ia supernovae. We note that the two well-observed Type Ia supernovae in Fornax, if placed at the Cepheid distance to the possible Fornax spiral NGC 1365, are apparently too faint with respect to the Calán/Tololo sample calibrated with the five Type Ia supernovae with Cepheid distances to the host galaxies.